It is well known that very large amounts of lubricating oils, e.g., engine oils, transmission oils, gear box oils, etc., find their way into the natural environment, accidentally and even deliberately. These oils are capable of causing much environmental harm unless they are acceptably biodegradable. For this reason there is increasing emphasis in this country, and abroad, to develop and employ high performance lubricant base oils which are environmentally friendly, or substantially biodegradable on escape or release into the environment.
Few hydrocarbon base oils are environmentally friendly though their qualities as lubricants may be unchallenged. The literature stresses the superior biodegradability of ester based lubricants, natural and synthetic, over hydrocarbon based products. However there is little or no emphasis on performance. Few references are found relating to the biodegradability of hydrocarbon lubricants. Ethyl Petroleum Additives's EP 468 109A however does disclose the biodegradability of lubricating oils containing at least 10 volume percent of a "biodegradable liquid hydrocarbon of lubricating viscosity formed by oligomerization of a 1-alkene hydrocarbon having 6 to 20 carbon atoms in the molecule and hydrogenation of the resultant oligomer." Apparently hydrogenated oligomers of this type have unexpectedly high biodegradability, particularly those having at least 50 volume percent dimer, trimer and/or tetramer. Ethyl Petroleum Additive's EP 558 835 A1 discloses lubricating oils having similar polyalphaolefin, PAO, components. However, both references point out performance debits for the synthetic and natural ester oils, such as low oxidative stability at high temperatures and poor hydrolytic stability. British Petroleum's FR 2675812 discloses the production of biodegradable PAO hydrocarbons base oils by dewaxing a hydrocracked base oil at low temperatures.
There is a clear need for biodegradable high performance hydrocarbon base oils useful as engine oil and industrial oil, or lubricant compositions which are at least equivalent to the polyalphaolefins in quality, but have the distinct advantage of being more biodegradable.